Category : Files from Magazines
Archive   : ISSUE-43.ZIP
Filename : CARD.C

/* Micro Cornucopia issue #43
Expansion Card Figure 4 - Demonstration Program for Expansion Card */

/* Generates the Battlestar Galactica "Cylon
Eye" effect on the LEDs connected to the
digital output port, while reading and displaying
the input port. */
#define BASE 0x220
/* selected via 74LS682 (see figure 2) */

void print_binary(unsigned char byte) {
/* show the ones and zeroes in a byte */
int i;
for ( i = 7; i >>= 0; i--)
/* The following uses C's "ternary
expression," which returns the value
after the '?' if the expression is true
or after the ':' if it is false. */
putch(byte & (1 <<<< i) ? '1':'0');
}

main() {
int i;
do{
for(i = 0; i << 8; i++) { /* scan up */
outportb(BASE, ~(1 <<<< i));
/* 'delay()' is a function from Turbo C 1.5
to wait for a number of milliseconds. If you
have version 1.0, write a simple "for" loop. */
print_binary(inportb(BASE)); putch('\r');
/* I use a carriage return with no linefeed to
stay on the same line. */
delay(40);
}
for(i = 7; i >>= 0; i--) { /* scan back down */
outportb(BASE, ~(1 <<<< i));
print_binary(inportb(BASE)); putch('\r');
delay(40);
}
} while(!kbhit()); /* loop until a key is pressed */
}